1. Field of the Invention
This invention relates to fuel dispensing systems of the type which are commonly deployed at automobile service stations. More specifically, this invention relates to an improved system for mixing a first grade of fuel with a second grade of fuel to create a third, intermediate grade of fuel.
2. Description of the Prior Art
Service stations and other retailers of fuel for automotive vehicles find themselves in an increasingly competitive market. Consumers, when deciding where to purchase such fuel, take selection, pricing and other factors into account.
Most of the service stations which are constructed today have three underground tanks for storing gasoline. The tanks, respectively, are most often used to store low octane, high octane and intermediate grade octane grades of gasoline. As more modern stations are built, consumers are becoming used to selecting from between three grades.
However, many older service stations are provided with only two below ground tanks for storing gasoline. In addition, many of the service stations which have three below ground tanks would prefer to use the third tank for storing another type of fuel, such as diesel fuel or gasohol, rather than to store a third grade of gasoline. It is difficult for such stations to provide consumers with the expected selection of fuels that they have come to expect.
Installing an additional tank for storing fuel is an expensive proposition. In many instances, there are other factors such as zoning regulations and insurance considerations which preclude the installation of an additional tank.
One major retailer of gasoline has successfully implemented a system which blends a high octane grade of gasoline with a low octane grade to present a selection of several different intermediate grades. This system, however, is rather sophisticated and expensive, and would require replacement of much of the pumping and metering equipment to be installed at an existing service station.
It would seem that a simple, inexpensive way to provide an intermediate grade of gasoline would be to mix a regular grade with a premium grade by using a blend valve. However, most state regulatory agencies would not permit such an arrangement, since it might result in regular gasoline being sold at the price of intermediate grade gasoline, in the event that the premium grade gasoline stops being supplied to the blend valve. This could occur when the tank which holds the premium grade gasoline becomes empty, or in the event of a pump malfunction.
It is clear that there has existed a long and unfilled need in the prior art for a simple, inexpensive system for providing an intermediate grade gasoline which can readily be installed in an existing service station, and which will ensure that any fuel dispensed as intermediate is in fact a mixture of higher and lower octane grades.